A prior art is described while referring to FIG. 6 to FIG. 8. FIG. 6 is a block diagram of a conventional column combination switch for automobile. Reference numeral 19 is a column combination switch main body, and reference numeral 20 is a light control switch unit, in which various switches are incorporated including the light switch, dimmer-passing switch, and turn switch. Reference numeral 21 is a wiper control switch unit, which accommodates various switches relating to the wiper including the front and rear wiper switches and washer switch. Reference numeral 22 is control means. Reference numeral 23 is a connector for communicating between the column combination switch and external devices by signals, and these signal communications are realized by a multiplex transmission system.
FIG. 7 and FIG. 8 are system diagrams of remote keyless entry system. In FIG. 7, reference numeral 12 is a transmitter main body of remote keyless entry system, reference numeral 13 is a signal generator for generating an aerial propagation signal, reference numeral 14 is a memory unit storing specific information, reference numeral 15 is a power source of the transmitter main body 12, reference numeral 16 is a transmission circuit for converting the output electric signal from the signal generator 13 into a radio signal and transmitting, and reference numeral 17 is a operation switch of the transmitter main body 12. Reference numeral 24 is a receiver main body, 25 is a power source unit, reference numeral 26 is a memory unit storing specific signals, reference numeral 27 is a comparator for comparing with received specified information, reference numeral 28 is control means, and reference numeral 29 is a receiving unit, which is connected to the control means 28. The receiving unit 29 of the receiver main body 24 is accommodated in the door of an automobile main body 31 as shown in FIG. 8, and a controller 30 for locking and unlocking the door is also incorporated in the door.
In this conventional system, the mutual relation of constituent elements and operation are described below. When the switch units 20, 21 of the column combination switch are manipulated, signals showing switch positions of the switch units 20, 21 are put into the control means 22, and the control means 22 processes these signals, and communicates with the external system through the connector 23. On the other hand, in the remote keyless entry system, by pushing the operation switch 17 of the transmitter main body 12 side, the signal generator 13 issues information of the memory 14, and transmits the information specified by the transmission circuit 16. In the receiver main body 24, specified information is received in the receiving unit 29, and the processed signal is compared with the specified information stored in the memory unit 26 in the control means 28 by the comparator 27, and when the both are matched, a door lock or unlock signal is issued to the controller 30, so that the vehicle door is locked or unlocked.
That is, without having to insert the key into the keyhole in the door, the specified information is transmitted from the transmitter main body 12, and compared with the specified information stored in the receiver main body 24 at the vehicle side, and when the both are matched, the door is locked or unlocked. When attempted to lock or unlock the door by inserting the key into the keyhole in the door, if carrying something in both hands or in the nighttime, it is hard to insert the key smoothly into the keyhole in the door, and it takes much time, or the vehicle may be scratched by the edge of the key. Instead of the key, by transmitting the specified information from the transmitter main body 12 to the receiver main body 24 at the vehicle side, the door is locked or unlocked. Therefore, by transmitting specified information from the transmitter main body 12, and comparing the specified information received in the receiver main body 24 and the specified information stored in the memory unit by an electronic circuit, the door can be locked or unlocked. This system may be also applied in various control devices, such as the trunk room lid locking and unlocking device, windowpane opening and closing device, or engine starting device.
Thus, in the remote keyless entry system, the signal from the transmitter main body 12 is received by the receiving unit 29 built in the door, and the door is locked or unlocked by comparing process, but since the receiving unit 29 in the door is surrounded by metal panels, which makes it hard to receive radio waves, and in the signal receiving range, the distance from the receiving unit 29 is short, and the receiving direction is also limited.